MB Raines, our widely published yeast expert graciously lent us her expertise inthis guide to everything you need to make yourself a yeast rancher and a growerof happy yeasts.

Yeast is that wonderful microbe which converts sweet wort into an enjoyablealcoholic beverage.

In addition to converting sugar to alcohol, yeast can alsoinfluence the taste, flavor, bouquet, and even the color of beer.

They do this bysecreting a variety of compounds at very low levels.

Different yeast strainsproduce different levels of these compounds and therefore impart their ownsubtle characteristics to the wort in which they are pitched.

Although yeasts mayall be the same species,Saccharomyces cerevisiae,

theyare not created equal.

Indeed a bread yeast does not makegood beer and the same may be said forsome wine yeasts.

Beer yeasts also differ and anyone who has split a batch ofbeer and pitched different yeasts will attest to the difference they can have inbrewing.

So just as hops, malts, and water must be chosen for a specific beer, somust the yeast.

The propagation and maintenance of yeast at home adds yetanother level of control to the brewing process, allows for experimentation, andaids in the consistent production of unique high quality beers.

The development of pure yeast strains and their importance in the brewingprocess has been going on for over a century and is still an active area ofresearch.

In 1883, Emil Christian Hansen described the first techniques forsuccessfully isolating single yeastcells and propagating them to a larger scale.

This was a landmark finding since up until then all yeasts were a mixturecontaining various forms of brewing yeast, wild yeast, bacteria, and molds.

Brewing with these mixtures of micro-organisms was difficult.

Beer spoiling wascommon and there was wide variability in beer quality.

Hansen's techniqueschanged all that and were quickly applied to improving large scale beerproduction; first in the Carlsberg brewery and a few years later in Americanbreweries.

Current propagation techniques remain similar to those first describedby Hansen.

Further characterization of yeast physiology and fermentationtechnology, however, have also influenced the current methods used topropagate and maintain yeast.

The following is a discussion of some of theseaspects of yeast physiology and fermentation and how it applies to homebrewingpractices.

Methods for maintaining yeast and their effectiveness with regards toyeast viability and stability will also be discussed.

Principles of Yeast Growth and Fermentation

Yeast is a facultative anaerobe which is just a fancy way of saying that it cansurvive and grow in the presence (aerobic) or absence (anaerobic) of oxygen.

The presence of oxygen determines the metabolic fate of the cell.

In terms of theyeast cell, its survival, growth and metabolism is optimal in the presence ofoxygen.

In this case, yeast will rapidly grow to high densities and will convertsugar (glucose) to carbon dioxide and water.

Under anaerobic conditions, yeastgrows much more slowly and to lower densities and glucose is incompletelymetabolized to ethanol and carbon dioxide.

It is important to realize that optimalyeast growth is distinct from fermentation.

Therefore, the conditions andmethodologies used for propagating and maintaining yeast need not be identicalto those used for fermenting wort.

The purpose of a yeast starter is not toproduce an enjoyable fermented beverage but rather to produce a sufficientquantity of yeast for subsequent

fermentation.

Propagation conditions should besuch that a maximal amount of yeast is produced which provides optimalfermentation performance once pitched.

What do we mean by fermentationperformance?

The main criteria for fermentation performance isbased on therate and extent of fermentation as well as the production of a beer with abalanced sensory profile with no off-flavors/aromas or inappropriate esters.

Theformer refers primarily to attenuation (technically referred to as the apparentattenuation) and is usually indicated by the percent reduction in gravity or:

Apparent Attenuation =

(O.G.-

F.G)

(O.G)

For a normal 1.050 original gravity wort, the terminal gravities should be near1.012 or 76% attenuation.

Apparent attenuation between 70-85% are normal formost yeasts.

Also fermentation should occur rapidly and be completed within 3-5days.

Factors influencing yeast growth

Several

factors influence both yeast growth (and fermentation) and thereforeshould be considered when propagating and maintaining, and yeast.

The mostimportant are oxygen, pH, temperature, and wort composition.

Oxygen.

As mentioned above oxygen or aeration

is essential for good yeastgrowth and is the driving force behind many aspects of yeast metabolismincluding fermentation.

Oxygen is quickly absorbed by yeast and is used tosynthesize unsaturated fatty acids and sterols which form the cell membrane.

These molecules are important for both growth and fermentation and serve as ameans of storing oxygen within the cell.

They are also necessary for increasingcell mass (growth), improving the overall uptake of nutrients, and determiningalcohol tolerance.

Oxygen also stimulates synthesis of molecules necessary foryeast to metabolize and take up maltose, the primary sugar in wort.

What does this means in terms of brewing.

Well since oxygen directly correlateswith rapid growth and increase in yeast mass (cell number), aeration during yeastpropagation should increase the overall number of yeast cells.

In otherwords,your starters need to be well-aerated.

I have been a long-time advocate of notusing airlocks on my starters, slants, etc.

In fact, I like to shake my starters asmuch as possible.

This will not only help introduce air into the wort, but will alsokeep the yeast in suspension and exposed to all the nutrients.

Alternatively youcan intermittently inject air or oxygen into a starters using

a sterile filter andaeration stone.

Foaming is usually a problem and therefore aeration is usuallyintermittent.

Another alternative which I use quite often is to continuously stirstarter cultures.

A magnetic stir bar is placed in the starter vesseland the vesselis put on a magnetic stir plate.

The stir plate causes the bar to rotate therebymixing the contents of the starter vessel.

Most stir plates have a dial so that youcan adjust the speed at which the bar spins.

In each case the tube or vessel isloosely capped so that gas can be exchanged.

Comparison of the number of yeastcells in starters which were mildly aerated (shaken intermittently), moderatelyaerated (injected with air intermittently) or highly aerated (continuously stirred)suggest that an increase in aeration/agitation does correlate with an increase inyeast cell number (Figure 1).

Continuous agitation/aeration can yield as high as a10-

to 15-fold increase in yeast cell number.

This translates into a 10-

to 15-foldhigher pitching rate than what is observed with a traditional airlocked starter.

This means you can generate a much larger amount of yeast using less wort!

Figure 1.

Effect of aeration on yeast cell number.

500 ml of BrewTek Superwort

was pitched with a saturated 10 ml superstarter culture of BrewTek yeast andincubated at room temperature (75 °F) for two days.

Cultures were either shaken3-6 times a day, aerated with BrewTek aeration system for several minutes (foampermitting) 3-6 times a day, or continuously stirred on a magnetic stir plate.

Yeastcell concentration was determined on

the BrewTek hemacytometer.

Traditionalstarter (with airlock) were taken from numbers published by Ray Daniels in HBD#1746 using Wyeast packet as inoculum.

In terms of fermentation, aeration is also important but only in the early stages(first 6-24 hours).

Aeration in later stages can oxidize beer constituents and leadto the development of off-flavors.

Since aeration sets the stage for maltose

fermentation and alcohol tolerance, it is easy to envision why insufficient aerationcould lead to stuck fermentations or incomplete fermentations.

Incompletefermentations can be manifested as either high finishing gravities or theproduction of off-flavors especially diacetyl, acetaldehyde, and hydrogen sulfide.

Insufficient aeration is also associated with excessive ester formation.

Theprofound effect of aeration on yeast is further illustrated in studies where yeastfrom a poorly aerated beer was repitched into aerated wort and still did notperform well.

Thus insufficient aeration can have a long-lasting effect on yeast.

In general, it is difficult for homebrewers to achieve sufficient oxygen levels.

Thelevels of oxygen necessary for optimalfermentation vary depending on the yeaststrain.

Ale strains usually need between 8-12 part per million (ppm) while lagerstrains require slightly higher amounts (10-15 ppm).

At atmospheric pressurethe maximum level of dissolved oxygen in wort is approximately 8 ppm and thesaturation level decreases further as the gravity of the wort increases.

Thusunless special steps are taken to introduce air or oxygen into the wort, it isdifficult for homebrewers to achieve adequate aeration.

Recent studies have

shown that oxygenation is by far more efficient than aeration.

Injection of oxygenthrough a 2 micron diffusing stone can actually supersaturate the wort with 10-12ppm of dissolved oxygen being reached in 5 gallons of wort by a single 60 secondblast of

oxygen!

Temperature.

Another important factor which influences yeast growth andmetabolism is temperature.

Temperature is somewhat neglected in terms of itsrole in influencing growth rate and fermentation performance.

Most brewingyeasts will actually grow and ferment at temperatures up to 98 °F (37 °C).

Thesehigh temperatures are not optimal for yeast propagation or fermentation, sincethey produce numerous esters and affect the overall viability and stability of theyeast.

86

°F (30 °C) is theusual temperature for the growth and propagation oflaboratory yeast but this is still too high for brewing yeast.

The temperature within the fermentercan be as much as 8 °F higher than outside of the fermenter during the first fewdays of fermentation.

So beers that are fermenting in refrigerators set at 65 °Fare most likely fermenting at about 72 °F.

Wort or media composition.

Wort (or media) composition also determines yeastgrowth and fermentation performance and is important in maintaining andstoring viable, stable yeast.

In terms of fermentation, standard brewing wortcontains most of the ingredients necessary for fermentation.

Problems arise onlyif the nitrogen composition is low.

This occurs only if a cheap or poor quality maltextract is used or if there are a large amount of adjuncts added.

In terms ofpropagation, the closer the starter media is to the fermentation wort the better.

A wort with an original gravity of 1.040 works well for most fermentations andis recommended for use in most brewing situations.

If pitching into a highgravity wort, a standard starter may get shocked from the change in osmoticpressure.

In this case a higher gravity starter (O.G. =1.065) may be necessary.

Lower gravity starters (O.G. = 1.020) are commonly used by homebrewers androutinely produce higher concentrations of yeast but do not perform well whenpitched into normal brewing worts.

Presumably this is due to osmotic shock.

The addition of yeast nutrients and certain salts can also improve yeast growthand are a worthwhile addition to starters.

Yeast nutrients usually are of twotypes, one which is ammonium phosphate-based, and the other which is aminoacid/peptide and vitamin-based (similar to the peptone and yeast extract in thelaboratory media described below).

Both serve the same basic function which isto increase the nitrogen content of the wort and yeast.

A mixture of differentnitrogen sources have been shown to enhance both growth and fermentation andsuggest that the amino acid/peptide-based nutrients may be more appropriatethan diammonium phosphate.

Also rapidly growing yeast such as those instarters have a higher than normal nitrogen requirement.

Thus starter wortsshould be supplemented with yeast nutrients so that nitrogen is not limiting.

Ammonium phosphate-based nutrients impart very little to the flavor profile.

Thesame is not true of the amino acid based extracts which tend to impart anautolyzed flavor (bloody, bouillon-like, and metallic) if used in excess (greaterthan a Tablespoon per 5 gallons).

Thus amino-acid based nutrients should

beused sparingly (if at all) in the fermenter.

This is an important consideration whenmaking meads since honey is very low in nitrogen and delicate in flavor.

Therefore diammonium phosphate is the preferred nutrient in meads although asmall amount of

We have recently tested the effects of a variety of food-grade aminoacid/peptide-based nutrients on yeast growth (Figure 2).

These experimentsindicate that the addition of certain yeast nutrients (especially nutrients #3 and 4)can increase the rate ofyeast growth but not the overall concentration or yield ofyeast.

Thus the addition of yeast nutrient to starters can help accelerate theirgrowth.

This is important for homebrewers since we rarely sterilize our worts andrapid growth is necessary for the yeast to take it over the starter before anypotential bacteria can grow.

Unlike the fermenting beer,

yeast nutrients can beadded at relatively high concentrations (1% or about 1/4 tsp per quart) to starterssince flavor is not an issue. If you are worried about the flavor of the startercontributing to your beer flavor, you can always let the yeast settle and decant offthe majority of the liquid.

During this time there are no apparent signs offermentation or growth.

The yeast are becoming acclimated to their newenvironment.

If the previous media (or starter) is similar to this new one,acclimation will occur rapidly and the lag phase will be short.

If there are majordifferences in the gravity, temperature, or wort composition, the yeastmay besurprised or shocked and it may take some time to adjust to this newenvironment.

Major changes occur within the yeast at this time, they areabsorbing all of the oxygen in the wort, using it to synthesize all the enzymes andother metabolic machinery necessary for growth and fermentation, and storingoxygen up in the form of sterols for later use.

This stage is critical to fermentationand should occur as rapidly as possible, preferably within a few hours.

II)

The second phase is theaccelerating growth phase

during which yeast cellsstart to grow and divide.

Signs of fermentation will also become apparent.

Theyeast begin storing sugar in the form of glycogen for later use.

III)

The third phase is theexponential phase

where yeast reproduction andmetabolism is in high gear.

Cells are dividing every 90-

180 minutes andfermentation begins.

During this time the number of yeast cells may increase asmuch as 1000-fold (or 3.0 logs) within 24 hours.

The extent to which the cellsdivide isdictated primarily by the pitching rate.

If appropriate pitching rates areused, the yeast are pitched at high concentrations (5-15 million yeast cells perml) and undergo approximately 3 generations (23-

or an 8-fold increase in cellnumber) to yield 80-100 million cells per ml.

100 million cells per ml is about themaximal concentration of yeast attainable in fermenting wort (Figure 2 &mp; 3).

Fermentation is also very active and a krausen may be beginning to form.

IV)

The fourth phase is thedecelerating growth

which should occur 12-24 hoursafter pitching.

At this time the oxygen is fully depleted and fermentation and CO2

production is taking over.

Fermenting wort should be in high krausen.

Maximalfermentation occurs during 12-48 hours;

heat is being generated and thereshould be rapid CO2

evolution (bubbling).

V)

Finally several days later, the yeast enter astationary phase.

During this timethe fermentables and nutrients are completely consumed.

All yeast growth hasstopped and they are beginning to fall out of suspension or flocculate.

The steroland glycogen stored up during early growth are beginning to be broken down andused to continue growth.

Prolonged exposure in this phase (weeks) can lead toautolysis or total breakdown of the cell.

Propagating procedures for the

preparation of pitching yeast

Why are these growth curves important with regard to brewing.

Basically this iswhat is happening in your starter.

When a small amount of yeast from a slant isinoculated to a tube containing 10 ml of wort or media, it will undergo thegrowth curve shown in Figure 3 over a 1-3 day period.

The precise length oftime will vary depending on the yeast strain, how old the slant is, the media used,the level of aeration, etc.

Note that use of a larger starting volume than 10 ml willincrease the amount of time it takes to reach the stationary phase.

10 ml is agood volume since it is small and will reach saturation in a short amount of timeand therefore should minimize potential contamination.

Now that we have an idea of how much yeast is in a 10 ml culture and how fast itwill grow.

We can start estimating how large a volume of yeast we need to pitchinto a fermenter and how long it will take to reach that volume.

This brings us topitching rates.

Pitching rates have been shown to have a profound effect onfermentation performance and are one of the main factors which contribute toconsistency between batches.

The pitching rate is just the amount of yeastadded to the fermenter.

It is usually expressed as the amount of yeast found in1 ml of wort after pitching.

The recommended optimal pitching rates are 6-10million cells/ml for ales and 10-15 million cells/ml for lagers.

(George Fixrecommends 10 million cells/ml for ales, 15 million cells/ml for lagers.)

Highergravity worts require even higher pitching rates.

Ale pitching rate

= 6-

10 million cells/ml

x

(1-

O.G)

48

Lager Pitching rate = 10-

15 million cells/ml x

(1-

O.G)

48

For example a 1.096 gravity ale wort should be pitched with 14-20 millioncells/ml.

What does this mean in plain English.

A 5 gallon fermentation containsapproximately 20,000 ml.

This means that for 1.050 gravity ale you would needto add between 120 billion (20,000 ml x 6 million cells/ml) and 200 billion cells(20,000 ml x 10 million cells/ml).

Table 4.

Pitching Yeast Characteristics

Yeast Type

Conc.

(millions/ml)

Volume

(ml)

TotalYeast

(billions)

Pitching ratefor 5 gal‡

(m楬汩潮猯o氩

噩慢楬楴i¶

(buds)

Dry (5 g)

620

200

124

(1011)*

6.2 (4.96)

80% (0%)†

䱩Lu楤i⌱

㜱

㔰

㌮3

⠱-㔩*

〮ㄸ (〮〴㔩

㈵┠%〥0

䱩Lu楤i⌲

㔸

㔰

㈮2

〮ㄴ㔠(〮〲㤩

㈰┠%㔥5

却慲瑥S

(獨慫敮)

㘰

(㈰)*

㔰5

㌰

(㄰)*

ㄮ㔠(ㄮ㐳)

(〮㔩*

㤵┠(㄰〥0

却慲瑥S

(慥牡a敤)

㤲

㔰5

㐶

㈮㌠(㈮㈵)

㤸┠(㄰〥0

却慲瑥S

(獴楲s敤)

ㄸ1-㌶3

㔰5

㤰-ㄸ1

㐮4-㤠(㐮㔩

㄰〥0(㄰〥0

¶

Based on exclusion of methylene blue.

†

Rehydrated yeast may exhibit altered methylene blue uptake.

*

Data adapted from those published by Ray Daniels in HBD #1746.

Thisdifference may be due to

intermittent shaken as well as media, etc.

‡

Pitching rate based on total yeast; numbers in parenthesis are corrected forviability.

This is alot

of yeast!!

So how do we go about propagating 200 billion yeast cellsso that we can hit this pitching rate.

Above is a table which shows the yeast cellcounts for various yeast sources as well as for 2 cup (500 ml) starters propagatedin nutrient fortified wort (see Table 3 for recipe).

Aside from dry yeast, the onlymethod which can yield a suitable pitching rate with two cups is the stir platemethod.

This is my method of choice since it is efficient and non-invasive whichmeans that I have minimal chances of infection during propagation.

The maindisadvantage is that stir plates are expensive ($75-$150 new) although you maybe able to find some relatively inexpensive ones at a scientific surplus orelectronic stores.

Most homebrewers start out pitching a Wyeast packet.

How much are youactually underpitching with one of these 50 ml pouches?

Assuming all the yeastin a Wyeast packet are viable (only about 25% truly are!), we are adding only 50ml of about 60 million/cells per ml.

This translates

into a pitching rate of 150,000cells per ml (Table 4).

Thus with a single Wyeast packet you are underpitchingby a factor of at least 35 for ales and almost 100-fold for lagers.

What is the bigdeal about underpitching.

Well remember that very littleyeast growth should goon in the fermenter.

There should be no more than 3 or 4 cell division whichshould take place during the first few hours of fermentation.

If underpitched theyeast will spend much more time trying to grow to adequate quantities.

Duringthis extended growth period the yeast tend to secrete more esters and fuselalcohols.

Moreover they may not have a sufficient number to adequatelymetabolize (digest) all of the fermentable sugars.

So what you end up with is abeer with off-flavors (such as esters, fusel alcohols, diacetyl, acetaldehyde) and ahigh finishing gravity.

Thus it is important to always make a starter and make it arelatively big one.

Remember thatyou want the yeast to spend most of theirenergy making alcohol not babies in a fermenter!!

So how big a starter do you need to make to hit the pitching rate.

Table 5estimates the approximate volumes of starters necessary to pitch 5 gallons ofwort at 10 million cells per ml.

The traditional airlock starter is very inefficient atgenerating yeast

and it would take almost 2.5 gallons (5-10 liters) of starter togenerate enough yeast for a 5 gallon batch!

Mechanically shaking your starterintermittently so as to resuspend the yeast is moderately effective and is theeasiest and most cost-effective thing you can do to improve the efficiency of yourstarter.

In this case you would need about a 0.75 gallon (3 Liter) starter togenerate enough yeast.

As mentioned above the stir plate is by far the mostefficient.

Table 5.

Approximate Starter volumes to achieve 10 million cells/ml.

Starter treatment

Conc.

(millions/ml)

Starter Volume

for 5 gallons

traditional

20

10 quarts

shaken

60

3.3 quarts

intermittentaeration

92

2.2 quarts

continuous stirring

180-360

0.75 quarts

The next issue is how long will it take to generate that big starter and how do I goabout doing it.

Once we have a 10 ml saturated culture going it should take only afew days to reach these volumes.

Close examination of Figure 3

indicates thatyeast should not be diluted more than 200 times the previous volume.

Inotherwords 10

ml should not be stepped up to more than 2 liters.

The rationalebehind this is simple.

During yeast propagation it is important to keep the yeastgrowing exponentially (Figure 3, phase III).

Diluting the yeast out too far will slowdown their growth and give bacteria a chance to overtake the culture.

Sincebacteria can grow as much as 6 times faster than yeast

(the average doublingtime for a bacterium is 20 minutes!), it is important to keep yeast growingrapidly.

If more than 1 or 2 liters of starter are required, it is best to do more thanone step-up.

In most cases it is best to do a 500 ml intermediate starter and after1-2 days step this up toas much as 1-2 gallons.

In each case the yeast shouldreach saturation in 24-48 hours.

Figure 4 outlines the two different propagationstrategies.

Figure 4.

Propagation of yeast for pitching.

The various steps involved inbuilding up enough yeast to pitch is depicted.

J. P. van der Walt and D. Yarrow, "Methods for isolation, maintentance,classification and identification of yeasts" in The Yeasts a taxonomic study(Elsevier Science Publishing Co., New York, New York 1984).

19.

Patrick Weix, "Frequently asked Question about Yeast"Zymurgy

17

(3) pp. ,1994

APPENDIX

Figure 8.

Culturing yeast from a bottle conditioned beer.

Schematic diagramshowing the steps necessary to purify, characterize, and maintain a culture from ayeast containing beverage.

At least one, if not two platings, may be necessary topurify the yeast.

Some breweries add special bottling yeast which differ fromthose used to ferment thebeer, therefore it is advisable to test brew (top) withthe yeast before trying to brew a large batch.

A similar strategy can be used tocharacterize samples collected at pubs.

In this case, it is useful to carry a fewempty slants with you to store yeast until you have time to propagate and purifythem.

A starter prepared thisway should be used within 1-2 days since it is not absolutely sterile.

Initiation-

10 ml mini-starter from yeast stock (superstarter).

These should begrown for 1-3 days; the mini-starter should be cloudy with lots of yeast.

Treatment-

Shake! Shake! Shake! This will give you 3 times more yeast.

Temperature

-Room temperature (~ 75 °F; ales can go up to 80 °F).

Time

-

Usually 2-3 days after starting with either a 10 ml culture or a Wyeastpacket.

It only takes 1-2 days if using a 10-fold step up.

Storage

-

If for some reason you couldn't use your starter, put it in therefrigerator and keep as cold as possible.

A day (or at least the morning) beforeyou want to use it, pour off the liquid and replace it with some fresh starter (1/4the original volume of the starter is more than enough) that has been boiled andcooled.

It should be ready to pitch within 4-24 hours.

Workshop Yeasts:

BrewTek CL-160British Draft Ale

-

A great yeast for accentuating the hop orroast character in a beer.

Relatively clean with very few esters but leaves a crispyet full bodied flavor dueto slight touch of diacetyl.

ESB F.G. = 1.011; 78%apparent attenuation.

BrewTek CL-150British Real Ale

-

Produces a distinct woody, almost mustyester character.

This doesn't seem to like the more complex sugars and thereforeis slightly underattenuating but leaves a fuller mouthfeel along with a slightlymalty finish.

This is a great yeast for low gravity beers like bitters and stouts andadds that creamy flavor typical of a British Real Ale.

For some reason this batchcame out slightly phenolic which is atypical of this yeast.

ESB F.G. = 1.017; 67%apparent attenuation.

Caledonian IPA

-

I cultured this from my favorite Scottish pub ale. It is a highlyattenuative strain that produces a complex fruity flavor which brings out thecaramel flavor of the malt.

A true Scottish strain, this would make an outstandingWee Heavy.

ESB F.G. = 1.007; 86% apparent attenuation.

================================================================

BrewTek CL-50California Pub Brewery Ale

-

A terrific all-round yeast that canbe used for almost any style beer.

It is unique in that it produces a big mouthfeeland helps accentuate the malt, caramel, or fruit character of a beer without beingsweet or underattenuating.

Again produces a nice full mouthfeel compared to someof the German Lager strains.

Ringwood

-

This is supposedly the same

as that used for Traquair House Ale,the classic Scotch ale.

It is a common used yeast in many of the east coastmicrobreweries including my personal favorite (Geary's Brewing Co.) and iscurrently being used at Santa Clarita (and Westwood Brewing) for all of their ales.

This is a true top fermenting yeast and a rigorous fermenter.

Its flavor profile isunique and leaves a distinct crisp flavor typical of English style ales (aka Bass) yetstill brings out the malt character in the beer; slightly fruity.

A great yeast for anyBritish Ales or reds.

This yeast also took a first place at Mayfaire with an all-grainbitter.

Fuller's Ale Yeast

-

This is a new yeast which is still in development.

It is highlyflocculent and may need rousing to finish out.

Rogue

-

From the brewery.

This is also referred to as Pac man yeast based onits performance in the fermenter.

This is yeast has not yet been full tested.

Let usknow what you think!

Rochefort

-

Cultured from one of the best (and my favorite) Belgian ale.

Sincethis is cultured from a bottle, your guess is as good as mine.

There's no guaranteethat this is the yeast the beer (a trippel) is fermented with but it's definitely worthchecking out.